Email address to send a read receipt to.
def get_read_receipt_to() -> str: ... def set_read_receipt_to(value: str) -> None: ...
read_receipt_to = property(get_read_receipt_to, set_read_receipt_to)
When this property is set, a Disposition-Notification-To header is added to the message. This property should be set to an email address which should receive the read-receipt.